Water-soluble polyesters which are curable to insoluble resins on exposure to heat or radiation are known. U.S. Pat. No. 2,845,402 discloses polyesters that on heating in the presence of a catalyst cure to insoluble resins and that are the reaction products of polyalkyleneoxide polyols and dicarboxylic acids. U.S. Pat. No. 4,073,777 discloses polyesters and polyesteramides that crosslink to water-insoluble resins on exposure to radiation and that are the reaction products of (1) at least one dicarboxylic acid, (2) at least one glycol, (3) sufficient sulfoaromatic dicarboxylic acid, dihydroxy, or diamino compound to provide water dispersibility to the reaction product, and (4) an unsaturated mono or dicarboxylic acid.
The water-soluble polyesters described in the above cited patents, although convertible on exposure to actinic radiation to water-insoluble resins, are high molecular weight compounds that are prepared by high temperature reactions requiring the heating of unsaturated reactants to temperatures of about 270.degree. C. for long periods of time. Such high molecular weight compounds have a high melt viscosity that adds to the difficulties encountered in handling the compounds. Also, because of the harsh and prolonged heating required in their preparation, the ethylenic unsaturation does not always survive.